146 patients in each arm were excluded due to ineligibility, incompliance, or presence of only isolated tumor cells in SNB (initially considered positive but later considered negative).

85% of patients completed the intended treatment in each arm.

With a median follow up of 6.1 years, the 5-year axillary recurrence rate after a positive SNB was 0.54% (4/744) with AD versus 1.03% (7/681) with ART.

The planned non-inferiority test was underpowered because of the unexpectedly low number of events.

The axillary recurrence rate after a negative SNB was 0.8% (25/3131).

There were no significant differences in 5 year OS between AD (93.27%) and ART (92.52%), p=0.3386.

There was also no significant differences in 5 year DFS between AD (86.90%) and ART (82.65%), p=0.1788.

AD was associated with significantly higher rates of lymphedema.

1 year: 40% AD versus 22% ART, p<0.0001

3 years: 30% AD versus 17% ART, p<0.0001

5 years: 28% AD versus 14% ART, p<0.0001

There was no significant difference in the risk of impaired shoulder function. However, there was a nonsignificant trend toward more early shoulder movement impairment after ART.

There were no significant differences in patient reported QOL outcomes in terms of arm symptoms, pain, and body image. There was a nonsignificant trend towards more difficulties with movement with ART and a trend towards more swelling with AD.

Author's Conclusions

5 year axillary recurrence rates after AD or ART were far below hypothesized, thus the trial was underpowered to detect a difference.

Nevertheless, AD or ART in patients with a positive SNB provide excellent and comparable local/regional control.

ART reduces the risk of short-term and long-term lymphedema compared to AD.

ART should be considered the standard of care.

Clinical Implications

This is a well-designed phase III randomized study that shows that compares ART with AD for treatment of patients with positive SNB.

Within the AD group, 244 (32.8%) of patients had additional positive lymph nodes. However, the study showed that ART provides equivalent local/regional control as AD while reducing the risk of lymphedema by 50% in patients with positive SNB.

While ART is equivalent to AD in patients undergoing breast conservation surgery or mastectomy with lower rates of lymphedema, longer follow-up is needed to assess the late effects of ART on lymphedema, shoulder dysfunction, and QOL.

Finally, there is a large overlap between the characteristics of patients enrolled in this study and the ACOSOG Z0011 study where no axillary nodal treatment was given. Both studies included largely postmenopausal women with T1-2cN0 tumors with 1-3 positive nodes. By applying the Z0011 criteria to the patients on the AMAROS study, one might argue that a large percentage of women on this study did not need either ART or AD.